Place chocolate chips in small microwave-safe bowl. Microwave at HIGH (100%) 1 minute; stir. If necessary, microwave at HIGH an additional 15 seconds at a time, stirring after each heating, just until chips are melted when stirred. Set aside to cool.
Beat cream cheese, sugar and butter in large bowl on medium speed of mixer until creamy. Gradually add melted chips, beating on low speed until blended. Fold in whipped topping until blended; spoon into crust.
Refrigerate until firm. Garnish as desired. Cover; refrigerate leftover cheesecake.